Push–pull mode digital control for LLC series resonant dc-to-dc converters

摘要

This study presents the design and performance evaluation of the digital control adapted to an LLC series resonant dc-to-dc converter operating with wide input and load variations. The proposed control design correctly incorporates the wide-varying power stage dynamics and variable small-signal gain of a digitally controlled oscillator, thereby offering satisfactory converter performance for all the operational conditions. The proposed digital controller adopts the push–pull mode control scheme, which executes the control action two times in one switching period, to minimise the time delay and enhance the performance. Using a 150 W experimental converter, the performance of the proposed push–pull mode digital control is demonstrated in comparison with that of the conventional complementary mode digital control, which performs the control action only once in one switching period.